Chelsea manager Roberto Di Matteo says the Champions League will be harder to win this season than last year.
Chelsea begin their defence against Juventus on Wednesday, in a group also consisting of Shakhtar Donetsk and FC Nordsjaelland.
''We have three champions in our group, from Italy, Ukraine and Denmark, so it will be difficult," said Di Matteo.
"[The Champions League] this season is very competitive and probably even stronger than last year."
The last team to retain Europe's top competition was AC Milan when they won the competition in 1989 and 1990 but Di Matteo's initial focus is on reaching the knockout stages rather than matching that achievement.
"The objective is always to get past the group, that's our first target," said the Italian. "Once we are through, it's two-legged games."
Chelsea won the Champions league for the first time in their history when they beat Bayern Munich on penalties last season but Di Matteo insisted it was time to move on from that victory.
"When you are at a big club like Chelsea, there is always pressure to win trophies and bring more success," he said.
"Everybody was pleased we finally brought the trophy home to Stamford Bridge, but we have to look forward now, that's in the past."
Juventus are unbeaten in 42 league matches and veteran goalkeeper Gianluigi Buffon is confident the Serie A side can do well in this year's competition following Chelsea's success last season.
"We are back in the competition through the main door," Buffon said.
"We deservedly won the league. We came in full of confidence and pride. We have all the will and determination to prove we can do well."